Black-out head lamp



July 9, 1946. R. N. FALGE ET Al. 2,403,646

' BLAcKoUT HEADLAMP Filed April 29, 1945 2 smaila-sheet 1A nventors July 9 1945- R. N. FALGE ET A1.

:BLACKOUT HEADLAMP Filed April 29, 1945 ZVSh'eets-Sheet 2 .A

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jf# L www 5 zum A or..d .WN/Mmm Gttornegs Patented July 9,' 1946KV UN'VHEID STATES l A2,403,646 BLACK-QUT LAMP Robert N..F.a;lge, Geer-ge W. On'ksen, Jr., `and`William R. Goris,.Anderson, Ind., assignors to General Motors Corporation, Detroit, Mch., la corxporation of :Delaware Application April t9',

l The present invention relates generally to .vehic'le lamps and .more ,particularly to the-construction of aheadlamp adapted .for use on mili tary -or .civilian vehicles which must be operated at night in Acombat or .other .zones where it isA desired sito lprevent `the detection .ci the .vehicles by enemy aircraft.

The `principal obiec't of the invention is therelfore "to provide a headlamp .constructionwhich will afford only suela illumination of the roadway yas' 'has :been 'found `necessary .for .reasonably .sai-e operation of the vehicle andin which .all direct rays are Vadequately shielded to prevent observation vthereof from above.

Tosimp'lify and facilitate .the design .and manufacture of the present headlamp it is proposed .to .utilize a conventional 'formof reflector :such

vas may be moimted within'a standard .headlamp casing and obtain the desired light distribution and shielding by the provision of la llensiandshield of novel construction'. n g .l N

In the .embodiment .disclosed herein the shield consists essentially .of .a metal front `cover plate for the lens which is provided .a ,relatively restricted opening .for the passage .of lightrays with a forwardly projectinghood' above `this .open' ing and to obtain the desired beam pattern opening lis in the .form off a horizontally extendingA narrow window or slot of. irregular .contour end the portion of the lens which .is exposed through the .slot .is provided with refrac-.tingV suriaces aS will :be hereinafter described. .Y Y

several .features of .the present .invention will be .apparent .from the ollowing description Yof the embodiment illustrated intheaccompanyng drawings, y.in which: Y

n Figure lY is a vertical section .taken .substantially .on 'line Yl--fl of .Figure 2 with parts in elevation of VAan .embodiment of the .present .invention. 1

.Figure 2y is a .front .elevation on line .2-2` of Figure l with parts broken away. .Y y .Y

Figure 3 .isa .fragmentary rear :elevationof Ythe lens taken substantially on line .3-3 .of .Figure .1.

Figure 4 is an enlarged Vertical central section of va portion .of the lens and shield.

.Figure z5 .is van enlarged fragmentary .horizontal .section Yof ...the lens taken substantially on line '5-5 :of .Figure-4.

Figure .6 :is a diagrammatic view showing the :beam` pattern and the relation 'of the saine to .respective portions of the s-lot in the shield.

Referring first to the showing .in Figure l, the reflector .2, light bulb 4, flens v( and `shield i are ,preferably secured 'together to` constitute e, selif- Y contained unit which, Las wili be understood, :is

5 claims. (omen-48.4)

1943, serial No. 435,042

adapted to y'be Amounted*witl'iin ya Astandard headlamp casing having -suitablemeans to secure and support the same upon a vehicle. kThe reflector 2V maybe of conventional `parabo'loidal fform and isLprov-ided with an opening to 'receive' the base I0 of the .iight bulb ll which `is `secured rin the .reiiector kas by solder |2 viriththe bulb vii-lament located iat .the ifocal of 'the reflector -and with the .frontend v'of the .bulbeshielded as indii1Y0 Acated at Y-l-Ato cut 101i direct vrays' from the lament. y

-. The lens may be secured within 'the .openen-d of the reflector l2 by clamping the .marginalporltion l-' of the lens between an annular peripheral 415 flange L6 .on the Vshie1d-.8 and an annular seat v20 on the reflector with ,a sealinggasket .22 .of rubber or similar material interposed fbetween'the lens and reflector. As' shown .in Figure l 'the o pen end of the.' reflector may beexterided forwardly beyond the lannular seat and be clinched or spun over theV iiange I8 of the shield 18 as 'at 24 to secure the lens and shield to thereflector and also conceal and protect the vmarginal portion. 'l of the lens and the gasket '22. Toposi- .25 tion the `shield circumierentially with reference 'to fthe'lensthe lens may be `formed with spaced i recesses inthe outer vface oi the marginal portion i5, asindicated'at 25 in AFigure Z, 'to receive correspondingly spaced 'indentations such as indicated yat 28 in Figure '2 on the flange klil ofthe shield. Referring now tothe yconstruction of the lens `6 and'sl'iield B it will rst be noted that vthe shield -is provided with alight transmitting opening "in the form of a horizontally extending, relatively narrow window slot which kis 'indicated generally Aat 30. As will'be apparent 4from the showing 1in Figures land 2, thiswindow slot '32] is 'located above the longitudinal .axis fof vthe .reilecton .flens y and shield assembly, andthe .shield isprov'ided 40 with a forwardly projecting .hood 32 'which-may 'beisecur-ed as 'by spot-welding tothe shield. The ho-@c1132 isfsubstantialiy arc-shaped with the iront .end thereof closed :by a vertical wall s4. The 'flower edges of the :hood .and the `bottom edge of t5 the' window V"slot -3 are in a `plane inclinedY approximately r1 to the horizontal. Therefore vthe slot-is not .visibleto anyone above thisplane.

` Before .describing the'panticular contour of the window slot 30 and `the refracting-fsurfaoes .on the lens'i which arediscilosed herein itis desired to call attention to the principal requirements which shouid be satisiie'd to obtain the-.desired illumina.- tion and to developthe Ydesired beam pattern. The reiracting .lens surfaces must, for instance.,

66 provide .a .certai-ndegree of bot-h vertical and ,neril f zontal spread of the light emitted through the relatively narrow horizontal slot 30 and al1 of the light rays should be directed below the bottom of the hood 32 with the upper porti-on of the beam obtained from the bottom of the slot and the lower portionrof the beam from the top of the slot to avoid having the light blocked off by the hood. It is also desirable to obtain the so-called hot spot light from the central portion of the slot, that is, the portion located adjacent the transverse center of the slot which is closest to the center -of the reflector since the images from this portion of the reflector are of minimum vertical depth, and to obtain the light of maximum horizontal spread from portions of the slot adjoining the central portion so that this light will not be blocked off by the sides of the hood 32 near the shield 8.

As heretofore mentioned, the bottom edges (both front and sides) of the hood 32 and the bottom edge of the window slot 30 are in a plane inclined approximately 1 to the horizontal. This bottom edge 0f the slot 3D is straight but the upper edge is formed in several steps to thereby provide portions which diifer in vertical extent. A1- l.

though all portions of the slot constitute a single continuous opening in the shield 8, the'slot has been diagrammatically represented in Figure 6 as composed of separate openings or portions identified by the letters A to J, inclusive, in order to set forth the relation thereof to certain refracting surfaces on the lens 6.

Referring now to the construction of the lens 5, refracting surfaces are provided on the portion of the lens opposite and adjacent the slot 3Q of the shield 8. The desired vertical beam spread is obtained primarily by a single horizontal convex ilute 36 on the outer face of the lens and the desired horizontal beam spread is obtained by a plurality of verticalconvex flutes A to J', inclusive.

on the inner face of the lens.

As shown in Figures 1 and 4, the major portion of the shield 8 may be spaced from the iront face of the lens B but Athe portion of the shield adjacent the slot 30 is offset from the rest of the shield and so formed as to fit closely against the horizontal flute 36 on the lens so that there will be minimum space between the edges of the slot and the lens. for-drainage of any moisture or foreign mater1a1 which may accumulate in the space between the shield and lens, and to prevent the emission of any light rays through this drain opening the portion of the outer face and marginal portion 5.6 of n the lens below the flute 36 may be provided wlth a light impervious coating of black paint as indicated at 40 in Figure 2 or otherwise shielded to render the same opaque.

The general curvature of the horizontal flute 36 is such that light rays passing through the upper portions of the slot 30 will be directed downwardly to a greater extent than rays passing through the lower portions of the slot whereby the top of the beam pattern will be obtained from the bottom of the slot and the bottom of the beam pattern from the top of the slot to avoid interference with the hood 32. On reference to Figure 4 it will also be seen that the vertical curvature of the flute 36 is formed on two diferentradii with the upper portion of the ilute above the horizontal level diagrammatically indicated at Z formed on a radius r which is shorter than the radius r of the An opening 38 is 'provided in the shield,A

portion of the flute below this level to increase the extent of downward deflection and vertical spread 4 of those light rays that pass through the extreme upper portions of the slot 30. 4 l

The vertical beam spread is also dependent upon the vertical extent of the several portions of the slot 39 and the normal vertical spread of the horizontal ilute 36 is also modied by the vertical curvature of the flutes Af to J', inclusive, on the inner face of the lens, which curvature varies on different utes to obtain the desired vertical spread of the several areas of the beam pattern. As shown in Figure 5, the convex curvature of the different vertical llutes on the inner face of the lens is also not uniform but is designed to produce diiferent extents of horizontalV spread for different areas of the beam pattern as will be described hereinafter.

Referring now to Figures 5 and 6 which show the beam pattern and the relation of the several portions of the slot 30 and the inner ilutes associated therewith to the respective areas of the beam pattern, it will be seen that the ilutes A' to J ,Vinclusive, provide blocks of light Which superimpose upon one another to build up the beam pattern which is entirely below the horizontal as indicated by line X-X vwith the several areas symmetrically disposed with reference to the vertical center indicated byline Y-Y.

The center vertical ilutes D', E', F and corresponding portions D, E, F of the slot 3U provide the beam pattern area indicated at d which is of minimum vertical and horizontal spread and constitutes the so.called hot spot. The extent of horizontal beam spread is dependent upon the amount of convexity of these Vertical flutes and the extent of vertical beam spread is dependent upon both the Vertical depth of the. respective slot portions and the relative vertical curvatures of the outer' horizontal flute 36 and the inner flutes D', E', F. On reference to Figure 4 it will be noted that the vertical curvature of these particular inner flutes is substantially the same as that of the outer ilute so as to cancel out the vertical spread of the outer ilute to provide minimum vertical spread of the hot spot area d. It should perhaps be vpointed out that the vertical curvature of all of the inner lflutes is effective in modifying the vertical beam spread of the outer horizontal flute only with which are in substantially horizontal alinement with the slot 30 and the other portions of the inner flutes are shown as vertically curved because the formation of these flutes is facilitated by machining this form on the plunger used for manufacture of the lens. y

In the present embodiment which is in commercial use the hot spot area d has a horizontal spread of about 24 and a vertical spread of about 2:with the top of this area about 1 below the horizontal. The rest of the beam pattern is made up of areas which all have their upper limit about 1.5 below the horizontalbut vary in vertical and horizontal spreads as will be noted hereinafter. y

The beam pattern area indicated at g has substantially the same vertical and horizontal spread as the hot spot area `d and is obtained from slot portion G and inner ilute G which are similar to each of the slot portions D, E, F and flutes D', E', F except for a slight difference in the Vertical curvature whichy is such that the entire area g is positioned about .5 lower than area d. The area indicated at a is obtained from slot portions A, J vat opposite ends of the slot 30 and the inner flutes A', J' associated there-A with which have substantially no vertical curvature so that the outer ilute 35 provides a greater vertical spread for area d than that of areas d and g heretofore described. The vertical spread of area a is about 3 and the amount of conH vexity of utes A', J is such as to provide a horizontal spread of about 46.

The flutes B, C', H', I' are similar to ilutes A', J' with reference to the absence of any appreciable vertical curvature but the vertical depths of the slot portions associated therewith are increased to provide greater vertical beam spreads and the amount of convexity of such flutes also varies to provide greater horizontal spreads of the respective areas of the beam pattern. The flutes I and B' both provide a horizontal spread of the respective areas i and b of about 60 but the depths of the associated slot portions I and B are such as to provide a vertical spread of about 4 of area i and about 5.5 of area b. f

The utes I-I and C both provide a horizontal spread of the respective areas h and c of about 80. The slot portions H and C' are of such vertical extent that the upper ends thereof extend above the` level indicated at Z in Figure 4 to thereby expose respective portions of the outer iiute surface abo-Ve this level which has been heretofore Adescribed as being formed on a shorter radius than the flute surface below this level to thereby provide a substantial increase in vertical spread of areas h and c as compared to the other areas. The vertical spread of area h is about 75 and the increased vertical extent of slot portion C provides a vertical spread of about 10.5 for area c.

As has been described above, the seriesof vertical inner flutes A' to J', inclusive, are so formed and associated with the respective slot portions A to J inclusive, and the outer horizontal ute as to produce the desired beam pattern. The inner flutes are preferably convex as shown and 6 ent invention has been disclosed herein it will be apparent that the several features thereof may be separately employed in other embodiments and many changes will occur to those skilled in the art and are contemplated as within the scope of the invention and coveredby the claimsv ap pended hereto.

We claim: j l. In a blackout headlamp for vehicles, the

` combination with a reector and light bulb, of a lens having a plurality of vertical flutes, a shield n front of said lens, and a relatively narrow horin zontal slot insaid shield in line with said vertical utes, said slot being of irregular contour and having portions thereof in line with some of said ilutes of different vertical extent than portions n thereof which are in line with other ilutes.

described instead of concave to obtain the desired horizontal spread of the several beam areas in order to prevent light rays from one flute passing through the slot portions which are associated with adjacent flutes. To prevent uncontrolled light rays from passing through the end slot portions A and J, a vertical convex flute M is provided adjacent each of the flutes A" and J' as shown particularly in Figure 5 to converge the light rays adjacent the flutes A and J so that they will be intercepted by the shield 8.

Although it might be possible to obtain both vertical and horizontal beam spreads from comi 2.*In a blackout headlamp for vehicles, the combination with a renector and light bulb, of a lens having a horizontal flute with portions thereof formed on different radii, a shield in front of said lens, said shield having a portion thereof formed to engage said horizontal ute andy a relatively narrow horizontal light transmitting slot in the flute engaging portion of said shield.

3. In a blackout headlamp for vehicles, ythe combination with a reflector and light bulb, of a lens having a horizontal flute with portions thereof formed on different radii, a shield in front of said lens, and a relatively narrow horizontal light transmitting slot in said shield, said slot having the major part thereof in line with the portion of said flute .formed on one radius with parts of said slot extended vertically above said major part to expose portions of said flute formed on a different radius.

4. In a blackout headlamp for vehicles, the combination with a reflector and light bulb, of a lens having a plurality of vertical convex flutes, a shield in front of said lens, and a relatively narrow horizontal slot in said shield adapted to expose portions of said flutes, said slot being of irregular contour with a straight bottom edge and a stepped upper edge to provide slot portions of different vertical extents in line with certain of said flutes.

5. In a blackout headlamp for vehicles, the combination with a reflector and light bulb, of a lens, a shield in front of said lens, a relatively narrow horizontal light transmitting slot in said shield having the central portion thereof of less vertical extent than the end portions thereof, and refracting surfaces on said lens in line with said slot including a horizontal flute on the outer face of said lens and a plurality of vertical flutes on the inner face of said lens, said vertical flutes f having different radii withthe flutes of longer radii in line with the centralportion of said slot whereby light rays passing through this slot portion will producea hot spot area of minimum vertical and horizontal spread and light rays passing through other portions of said slot will produce beam areas of greater vertical and horizontal spreada ROBERT N. FALGE. GEORGE W. ONKSEN, JR. WILLIAM R. GORIS, 

